Hydrophilic carbon quantum dots assisting porous P(VDF–HFP) film for self-powered humidity sensing with high sensitivity and low hysteresis

Abstract

Being self-powered has become the development trend of electronic devices in the “double carbon” era. However, environmental humidity has a significant impact on the piezoelectric properties of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF–HFP)) based devices with self-powered potential, which encourages us to generate a new idea of constructing a flexible self-powered humidity sensor with porous P(VDF–HFP) film. Taking advantage of hydrophilic bonding and the induced effect from the incorporated carbon quantum dots (CDs), both the humidity sensitivity and piezoelectric performance of P(VDF–HFP) were greatly improved. The average contact angles were sharply reduced from 126.3° to 65.1° or 77.3° for two modeled CDs, which effectively lowered the hysteresis of moisture sensitivity. Furthermore, the output voltage of the constructed sensor presented a three-stage linear relationship with the environmental humidity. The flexible self-powered humidity sensor with high sensitivity and low hysteresis is expected to be applied in bio-medicine, environmental monitoring and other fields.